Flame-resistant urethane foams



United I States Patent O 3,159,591 FLAME-RESISTANT URETHANE FOAMSWilliam M. Lanham, Charleston,.W. Va., assignor to Union CarbideCorporation, a' corporation of New York No Drawing. Filed June 28,196.1, Ser. No. 120,181

, 23 Claims. (Cl. 260-25) tion, structural reinforcement, cushioning,electrical en-' capsulation and in domestic electrical equipment such asrefrigerators, freezers and the like. One formidable factor limiting thecommercial utilization and growth potential of the foamed urethaneproducts is their risk of flammability in applications Where hightemperatures and/ or exposure to fire may be encountered.

The present invention is based on the "discovery that "ice of asaturated aliphatic mono-, dior tricarboxylic acid, at temperatureswithin the range from about 50 C. to about 200 C., and generally attemperatures within the range between about 50 C. and about 100 C. It ispreferred to add the phosphorus-containing reactant slowly or dropwiseto a suspension of the anhydrous alkali metal salt of the carboxylicacid in an anhydrous solvent for the desired pyro-cornpounds untilapproximately one mol of the phosphorus-containing reactant has beenadded for each molecular equivalent of the said alkali metal salt. Thereaction mixture is washed with water and with a dilute'aqueous solutionof an alkali metal bicarbonate, and the oily layer which separates isstripped by distillation to kettle temperatures around 100? C. under apressure of'less than 2 mm. of mercury to remove the solvent and lasttraces of water. The residual product is secured in approximately pureform. n

The reaction involved in this method of preparation may be illustratedby the equation:

certain cyclic compounds which contain phosphorus are effective forimpartingflarne resistance to cellular polyurethane foams. It has beenfound that when cyclic pyrophosphates V are incorporated intopolyether-isocyanate reaction systems and the mixture conventionallyfoamed by the one-shot, semiprepolymer or prepolymer technique, thepolyurethane foams obtained thereby possess a substantial degree offlame resistance. Theachievement of flame resistance according to theinvention provides a valuable means whereby polyurethane.

foams of widely varyingandpreselected properties can. be readilyprepared which'are self-extinguishing in the AST M D-1692 flammabilitytest. V

The phosphorus compounds utilized for purposes of the invention areesters of pyrophosphoric acid wherein each phosphorus atom is in a fiveor six membere'dring consisting of carbon, oxygen and phosphorus. Thestrucwherein M designates a hydrocarbon radical of the formula' -CR R(CRR') CHR wherein R, R R R and R respectively, designates a member ofthe class consisting of hydrogen andthe alkylgroups, and n is ()or 1. i

- The phosphorus compounds also can be made by reacting at temperaturesaround 10 to 60 C. a 2-halo-2- oxo-1,3,2-dioxaphosphorinane or-dioxaphospholane with water in the presence of just enough of a base,preferablyture' of the cyclic compounds may be represented by thegeneral formula: R2\ R4 'identified aspyro-v2'-oxo-1,3,2-dioxaphosphorinanes andpyro-2-oxo-1,3,2-dioxaphosPholanes which can be prepared from2-halo-2-oxo-l,3,2-dioxaphosphorinanes and the corresponding2-halo-2-oxo-1,3,2-dioxaphospholanes by several methods. 7 I

According to one method of synthesis a-cornpound of the general formula:a

pyridine, totake upthe hydrogen chloride formed, according to thereaction washed with dilute aqueous sodium bicarbonate and then withWater. The washedfiltrate then is stripped by distillation to a kettletemperature of about 100 C. under an absolute pressure of less than 2mm. of mercury. The residual pyropho'sphate derivative is secur'able inhigh 7 purity. 1

Among the salts of saturated carboxylic acids useful in one ofthes'eprocesses formaking the phosphorus compounds are the alkali, metal saltsand ammonium salts of the fatty acids having one to eighteen carbonatoms,

such'as formic, acetic, propionic, butyric, hexoic, 2-ethylhexoic,capric, palmitic and stearic acids; corresponding di salts of oxalic,"glutaric, succinic, adipic, n pimelic and sebaccic acids; and tri saltsof tricarballylic acid.

' The 2-halo-2-oxo-1,3,2-dioxaphosphorinane and correspondingphospholane derivatives used in making the phosphorus compoundsconveniently are made by the dropwise addition of an alkane-1,3-d-iol oran alkane-1,2-

, 'diol, respectively, to a phosphoryl chloride or bromide,

preferably in approximately equimolecular proportions,

or to a solution of such a phosphoryl halide in an inert wherein R, R RR and R respectively, designates by:

drogen or an alkyl group, n is 0 or '1, and Haldesignates.

chlorine or bromine, is reacted,,under substantiallyan hydrousconditions .With theuanhydrous alkali metal salt 7 "hydrogen chloridesequestering agent, such as pyridine,

and an inert low-boiling solvent for the reactants, such as ethyl ether.Thus, 2-chloro-5-ethyl-2-oxo-4-propyl-1,3,2- dioxaphosphorinane wasprepared in high yield by slowly adding during 1.75 hours 584 grams (4mols) of 2 ethyl- 1,3-hexanediol to 614 grams (4 mols) of phosphorylchloride while maintaining the reaction mixture at 25 C. under 500 mm.of mercury pressure. The reaction mixture then was kept for one hour at25 C. under 350 mm. of mercury pressure and finally at 25C. overnight atmm. of mercury pressure thus eliminating the hydrogen chloride produced.The residual 2-chloro-5-ethyl-2- oxcr4-propyl-1,3,2-dioxaphosphorinanehad a chlorine content of 16.02% (theory=15 .65%) and a molecular weightof 232 (theory=226.6).

Among alkane-1,2-diols and alkane-1,3-diols useful in the production ofthe halogen-containing reactants are ethanediol-1,2; propanediol-l,2;butanediol-1,2; ethylethanediol-1,2; 1,2-dimethylethanediol-1,2;propanediol- 1,3; butanediol-1,3; pentanedio1-1,3; hexanediol-1,3; 2-ethylhexanediol-1,3 2-butyl-2-ethylpropanediol-1 ,3 and pentanediol-2,4.

In accordance with the invention, polyurethane foams which areself-extinguishing and possess a substantial degree of flame resistanceare prepared by mixing together a polyisocyanate and polyether, buildingup the urethane polymer network and thereafter developing the foamreaction. The cyclic pyrophosphates can be added to the liquidpolyether, the isocyanate or the polyether-isocya-e nate reactionmixture. The mixture is then foamed in the presence of a catalyst bymeans of a blowing agent such as water or a fluorocarbon.

The amount of cyclic pyrophosphate used for purposes of the invention isnot narrowly critical. The preferred amount should be suflicient toprovide a phosphorus content ranging between about 0.25% and 5.0% byweight based on the polyetherisocyanate reaction mixture. If desired,antimony trioxide may be used in conjunction with the phosphoruscompound to obtain optimum flame resistance. The amount of antimonytrioxide used genon the polyether-isocyanate reaction mixture.

wherein R is ethylene, propylene, butylene, or mixtures thereof and n isan integer such that the average molecular weight of the polyether is250 and higher.

Further included are polyethers prepared by reacting a 1,2-alkyleneoxide such as ethylene oxide, propylene oxide, butylene oxide ormixtures thereof with mononuclear polyhydroxybenzenes such asresorcinol, pyrogallol, phloroglucinol, hydroquinone,4,6-di-t-butylcatechol, catechol, orcinol, methylphoroglucinol,2,5,6-trimethylresorcinol, 4-ethyl-5,6-dimethylresorcinol,n-hexylresorcinol, 4-chloro-5-methylresorcinol, and the like; polyethersprepared by reacting 1,2-alkylene oxides or mixtures thereof with fusedring systems such as 3-hydroxy- 2-naphthol, 6,7-dihydroXy-1-naphthol,2-hydroxy-l-naphthol, 2,5-dihydroxy-l-naphthol,9,10-dihydroxyanthracene, 2,3-dihydroxyphenanthrene, etc.

Other polyethers which can be employed are those obtained by reacting1,2-alkylene oxides or mixtures thereof with polynuclear hydroxybenzenessuch as the various di-, triand tetraphenylol compounds in which two tofour hydroxybenzene groups are attached by means of single bonds or byan aliphatic hydrocarbon radical containing one to twelve carbon atoms.The term polynuclear as distinguished from mononuclear is used todesignate at least two benzene nuclei in a compound.

Exemplary diphenylol compounds include 2,2-bis(phydroxyphenyl) propane;bis(p hydroxyphenyl)methane and the various diphenols and diphenylolmethanes disclosed in US. Patents 2,506,486 and 2,744,882, respectively.

Exemplary ,triphenylol compounds which can be employed include thealpha, alpha, omega, tris(hydroxyphenyl)alkanes such as1,1,2-tris(hydroxyphenyl)ethanes;

. The active hydrogen-containing polyethers which are I used inpreparing the polyurethane foams include the linear and branched chainpolyethers which have a plurality of acyclic ether oxygens and containat least two hydroxyl groups. The polyethers are substantially free fromfunctional groups other than hydroxyl groups and have molecular weights,based on their hydroxyl value, ranging from 250 to 5000.

Illustrative polyethers include the polyoxyalkylene polyols containingone or more chains of connected oxyalkylene groups which are prepared bythe reaction of one or more alkylene oxides with acyclic and alicycliepolyols. Examples of the polyoxyalkylene polyols include thepolyoxyethylene glycols prepared by the addition of ethylene oxide toWater, ethylene glycol or di-' propylene glycol; polyoxypropyleneglycols prepared by the addition of propylene oxide to water, propyleneglycol or dipropylene glycol; mixed oxyethylene-oxypropylene polyglycolsprepared in a similar manner utilizing a mixture of ethylene oxide andpropylene oxide or a sequential addition of ethylene oxide and propyleneoxide; and the polyoxybutylene glycols and copolymers such aspolyoxyethyleneoxybutylene glycols and polyoxypropyleneoxybutyleneglycols, Included in the term polyow butylene glycols are polymers of1,2-butylene oxide, 2,3- butylene oxide and 1,4-butylene oxide.

Other acyclic and alicyclic polyols which can be reacted with ethyleneoxide, propylene oxide, butylene oxide or mixtures thereof to provideuseful polyethers include glycerol, trimethylolpropane,1,2,6-1exanetriol, pentaerythritol, sorbitol, glycosides, such asmethyl, ethyl, propyl,

butyl and 2-ethylhexyl arabinoside, xyloside, fructoside,

glucoside, rhammoside, etc. and polyethers prepared by the reaction ofalkylene oxide with sucrose, for example:

CHzO (R 0) 1111 OH20(RO)I1H 1,1,3-tris(hydroxyphenyl)propanes;1,1,3-tris(hydroxy-3- methylphenyl)propanes; 1,1,3-tris(dihydroxy 3methylphenyl)propanes; 1,1,3-tris(hydroxy 2,4 dimethylphenyl) propane;1,1,3-tris(hydroxy 2,5-dimethylphenyl)propanes; 1,1,3-tris(hydroxy 2,6dimethylphenyl)propane; 1,1,4 tris(hydroxyphenyl)butanes; 1,1,4tris(hydroxyphenyl)-2-ethylbutanes; 1,1,4 tris(dihydroxyphenyl)butanes;1,1,5-tris(hydroxyphenyl)-3-methylpentanes; 1,1,8-

I tris(hydroxyphenyl)octanes; 1,1,10-tris(hydroxyphenyl)- decanes, andthe like.

Tetraphenylol compounds which can be reacted with 1,2-alkylene oxidesinclude the alpha, alpha, omega, omega, tetrakis(hydroxyphenyl)alkanessuch as 1,1, 2,2-tetrakis (hydroxyphenyl) ethanes; 1, 1,3 ,3-tetrakis(hydroxy 3 methylphenyl)propanes; l,l,3,3-tetrakis(dihydroxy 3methylphenyl)propanes; 1,1,4,4 tetrakis (hydroxyphenyl)butanes; 1,l,4,4tetrakis(hydroxyphenyl)- 2-ethylbutanes;1,1,5,5-tetrakis(hydroxyphenyl)pentanes;

1,1,5,5-tetrakis(hydroxyphenyl) 3 -methylpentanes; 1,1,

5 ,S-tetrakis(dihydroxyphenyl)pentanes; 1,1,8,8 tetrakis- (hydroxy 3butylphenyl)octanes; 1,1,8,8-tetrakis(dihydroxy 3 butylphenyl) octanes;1,1,8,8-tetrakis(hydroxy- 2,5-dimethylphenyl)octanes;1,1,10,10-tetrakis(hydroxyphenyl) decanes; and the correspondingcompounds which contain substituent groups in the hydrocarbon chain suchas 1,1,6,6-tetrakis(hydroxyphenyl) 2 hydroxyhexanes; 1,1,6,6-tetralis(hydroxyphenyl) 2 hydroxy 5 methylhexanes;1,1,7,7-tetrakis(hydroxyphenyl)-3-hydroxyheptanes; and the like.

Other particularly useful polyethers which can be employed are theethylene oxide, propylene oxide, and butylene oxide adducts ofphenol-formaldehyde materials such as the novolaks. I

Novolaks are believed to be mixtures of polynuclear compounds of thediphenylmethane type of structure, such as 4,4'-dihydroxydiphenylmethaneand 2,4' dihydroxydiphenylmethane formed by the Baeyer reaction ofphenol and formaldehyde. In a typical synthesis, novolaks are preparedby condensing one mole of phenolic compound, such as phenol or cresol,with 0.8 mole of an aldehyde, such as formaldehyde or furfural, underacid conditions at a temperature around 160 C. to 170 C. The polynuclearproducts frequently contain 4 to 8 units and may contain 12 or moreunits. Novolaks, as such, are non-curable, thermoplastic resins.

Further included are polyethers prepared by reacting one or more of thealkylene oxides above noted with ammonia or acyclic polyamines such asethylenediamine, propylenediamine, butylenediamine, pentylenediamine,hexylenediamine, octylenediamine, nonylenediamine, decylenediamine;polyalkylene polyamines such as diethylenetriamine, triethylenetriamine,tetraethylenepentarnine, and the like. A particularly suitable polyetheris the propylene oxide addition product of diethylenetriaminerepresented by the formula:

wherein n represents an integar which provides an average molecularweight of 250 or higher.

Other suitable polyethers include the 1,2-alkylene oxide derivatives ofmononuclear primary amines such as o-, m-, and p-phenylenediamine; 2,4-and 2,6-diaminotoluene; 2,6-diamino-p-xylene; 4,6-diamino-m-xylene;2,4-diaminom-xylene; 3,5-diamino-o-xylene; isohexyl-p-phenylenedibenzoicacid, triaminodiphenyl ethers and sulfides such as2,4,4'-triaminodiphenyl ether; 2,3',4-triamino-4'-methyldiphenyl ether;2,3',4 triamino 4' methoxydiphenyl ether; and polyamines obtained byinteraction of aromatic monoamines with formaldehyde or other aldehydes,for example:

I I so 2011.0

. CED-NH:

R I NH! wherein R is hydrogen or an alkyl group.

Inaddition tothe above-described polyethers it is also within the scopeof the invention to blend varying amounts of polyfunctional compoundswith the polyethers before reaction with isocyanates. Such compoundsinclude, among others, alkylene glycols such asethylene glycol,diethylene glycol, triethylene glycol, tetraethylene glycol and thecorresponding propylene homologs such as propylene glycol, dipropyleneglycol, etc; saturated aliphatic-p'olyols such as glycerol,1,2,4-butanetriol, 1,2,6- hexanetriol, trimethylolpropane,pentaerythritol, etc.; acyclic amines such as triethanolamine;triisopropanolamine, etc.; acyclic polyamines such as ethylenediamine,diethylenetriamine, triethylenetetramine, and the like. Further includedare the ethylene, propylene and butylene oxide addition products of theabove noted aliphatic polyols and amines which have hydroxyl numbers inthe range of about 300 to 750. When admixed with the polyether, thismodification has the advantage of further diversifying the combinationsof characteristics obtainable in the ultimate foam product by increasingthe number of available cross-linking sites.

The molecular weight of the polyether used should range from about 250to about 5000 depending upon the characteristics desired in the foamedurethane product. As a general guide, cellular urethane foams of maximumrigidity are prepared by the use of polyethers having a 1 molecularweight range of about 1800 to 5000.

A variety of isocyanates may be employed for reaction with thepolyethers above described to provide urethane foams which can berendered flame-resistant according to the invention. Preferredisocyanates are polyisocyanates and polyisothiocyanates of the generalformula:

1,8 diisocyanato p menthane, xylylene diisocyanates,

(OCNCH CH CH OCH 1-methyl-2,4-diisocyanatocy clohexane, phenylenediisocyanates, tolylene diisocyanates, chloropheiiylene diisocyanates,diphenylmethane- 4,4'-diisocyanate, naphthalene-1,5-diisocyanate,triphenylmethane-4,4',4'-triisocyanate, xylene-a,rx'-diisothiocyanate,

and isopropylbenzene-u,4-diisocyanate. Further included are dimers andtrimers of isocyanates and diisocyanates and polymeric diisocyanates ofthe general formulaez.

in which x and y are two 'or more, as well as compounds of the generalformula:

' in which as is one or more and M is a monofunctional or polyfunctionalatom or group. Examples of this type include ethylphosphonicdiisocyanate, C H P(O) (NCO) :phenylphosphonic diisocyanate, C H P(NCO)compounds containing a SiNCG group, isocyanates derived fromsulfonamides [R(SO NCO) cyanic acid,

thiocyanic acid, and compounds containing a metal-NCG group such astn'butyltin isocyanate.

A particularly useful polyisocyanate is the product:

OCNOCHz-Q preferred procedure is the semiprcpolymer technique whereinthe polyether reactant is partially extended with excess isocyauate toprovide a reaction product containing a high percentage of freeisocyanato groups (20 to 35%) which is foamed at a later stage byreaction with additional polyether, catalyst and a blowing agent.

The amount of isocyanate employed will depend upon the density of theurethane foam and the amount of cross linking desired. In general thetotal -NCO equivalent to total active hydrogen equivalent should be suchas to provide a ratio of 0.8 to 1.2 equivalents of -NCO per equivalentof active hydrogen, and preferably a ratio of about 0.9 to 1.1equivalents.

The foaming operation is preferably effected by lique fied fluorocarbongases which have boiling points below about 80 F. and above 60 F. Theliquefied gases are saturated aliphatic hydrocarbons which vaporize ator below the temperature of the foaming mass. Such gases are at leastpartially fiuorinated and may also be otherwise halogenated.

Preferred blowing agents are the fluorocarbons such astrichloromonofiuoromethane; dichlorodifluoromethane,dichlorofiuoromethane; l,l-dichloro-l-fluoroethane; 1,1-difluoro-l,2,2-trichloroethane; and 2-chloro-1,1,1,2,3,3,4,4,4-nonafluorobutane. The amount of blowing agent used will vary withdensity desired in the foamed product. In general it may be stated thatfor 100 grams of resin mix containing an average NCO/ OH ratio of 1 to1, about 0.005 to 0.3 mole of gas are used to provide densities rangingfrom 30 to 1 lbs. per cubic foot. If desired, water may be used inconjunction with the blowing agent.

Catalysts that are suitable for accelerating the polyether-isocyanatereaction include a wide variety of organic tin catalysts, tertiary aminecatalysts and combinations thereof.

Among the organic tin compounds that deserve particular mention arestannous acylates such as stannous acetate, stannous octoate, stannouslaurate, stannous oleate, etc.; stannous alkoxides such as stannousbutoxide, stannous Z-ethylhexoxide, stannous phenoxide, o-, mandp-stannous cresoxides, etc.; dialkyl tin salts of carboxylic acids,e.g., dibutyltin diacetate, dibutylin dilaurate, dibutyltin maleate,dilauryltin diacetate, dioctyltin diacetate, and the like. Similarlythere may be used a trialkyltin hydroxide, dialkyltin oxide ordialkyltin dichloride. Examples of these compounds include trimethyltinhydroxide, tributyltin hydroxide, trioctyltin hydroxide, dibutyltinoxide, dioctyltin oxide, dilauryltin oxide, dibutyltin dichloride,dioctyltin dichloride, and the like.

Typical tertiary amine catalysts which can be employed includetrimethylamine, N-rnethylmorpholine, Nethyl morpholine,triethylenediamine, N,N,N',N'-tetramethyl- 1,3-butanediamine,triethanolamine, and the like. The tertiary amines may be used asprimary catalysts for accelerating the polyether-isocyanate reaction oras a secondary catalyst in cornbinationwith the above noted organic tincompounds.

It is also within the scope, of the invention to employ small amounts,e.g., about 0.001% to 5.0% by weight, based on the total ingredients, ofan emulsifying agent such as a siloxane-oxyalkylene copolymer havingfrom about to 80 percent by weight of siloxane polymer and from 90 to 20percent .by weight of alkylene oxide polymer, such as the copolymersdescribed in U.S. Patent 2,834,748. Although the use of an emulsifier isdesirable to influence the type of foam structure that is formed, thefoam products of the invention can be prepared without emulsifiers.

The following examples illustrate the best mode now contemplated forcarrying out the invention.

EXAMPLE 1 To an agitated suspension of 90 grams (1.1 mols) of anhydroussodium acetate in 400 grams of toluene there were added dropwise during20 minutes 227 grams (1 8 mol) of2-chloro-5-ethyl-2-oxo-4-propyl-1,3,2-dioxaphosphorinane whilemaintaining the reaction mixture at 100 C. during this period and for anadditional 30 minutes. The reaction mixture then was washed with 800 cc.of water, twice with dilute aqueous sodium bicarbonate solution, andagain twice with water. The oily layer which separated was withdrawn andstripped by distillation to a kettle temperature of 100 C. under apressure of less than 2 mm. ofmercury. The residual 5,5'-diethyl-2,2'-dioxo-4,4'-dipropylpyro 1,3,2 dioxaphosphorinane was secured in theform of a yellow liquid having the following properties: n =1.4657;specific gravity at 25/ 15:1.174; molecular weight (ebullioscopic)=374.9 (theory=398.4); percent P=15.51 (theory:15.55); percent (3:48.53(theory=4-8.23); percent H=8.11 (theory =8.10).

i CaH1 2 EXAMPLE 2 was recovered in 85% yield in the form of a brownwatersoluble liquid free from chlorine, and having the followingproperties: equivalent weight (by saponification)=69.5 (theory =64.5);percent 0:27.07 (theory=27.92); percent H='5.11 (theory=4.69).

EXAMPLE 3 Employing the reaction conditions described in Example 1, thereaction of 1 mol of 5-butyl-2-chloro-5-ethyl-2-oxo-1,3,2-dioxaphosphorinane and 1.1 mols of anhydrous sodium acetate in 400grams of toluene gave a 97% yield of 5,5'-dibutyl-5,5-diethyl-2,2'-dioxo-pyro 1,3,2 dioxaphosphorin ane,

CH2() in the form of a mushy solid having the following analysis:percent P: 14.25 (theory: 14.53); percent C=51.5 (theory=50.71) percentH==8.8 (theory=8.5 equivalent weight (by saponification) =200(theory=213).

EXAMPLE 4 Following the procedure in Example 1, 1 mol of 2-chloro-5,5-diethyl-2-oxo-1,3,2-dioxaphosphorinane was reacted with 1.1mols of anhydrous sodium acetate in 400 (theory-=6.41). A yield of 54%,,based upon the residual solid was purified by dissolving in 200- cc. ofdry acetone and precipitating by the addition of 500 .cc. of distilledwater. The white crystalline precipitate was removed by filtration,composited with the 101 grams of wet crystals, and dried under vacuum.2,2-dioxo-5,5,5, '-tetra-ethyl-pyro-1,3,2-dioxaphosphorinane was securedin 81% yield as a white crystalline solid having the following.properties: melting point=l82 l90 C.; percent purity (bysaponification)=98.4; percent P =.17.10 (theory=16.72); percent C=45.45(theory=45.40); percent H=7.60 (theory =7.62).

To an agitated suspension of 83 grams (1.01 mols) of anhydrous sodiumacetate in 400 grams of toluene held at 100 C., there were addeddropwiseduring minutes filtered. The filtrate Wasstripped by distillation to akettle temperature of 100 C. under a pressure of less I than 2 mm. ofmercury. The tan residue of 4,4-dimethyl-2,2'v-dioxopyro-1,3,2-dioxaphosphorinane had the following analysis:percent P=20.75 (theory=2l.66); percent -C=33.41 (theory=33.57); percent.H=5.59 (theory 10 fication)=180 (theory=199); percent yield=78 (basedupon the phosphorus-containing reactant).

EXAMPLE 8 heated at 50 C. for 6 hours, cooled and "filtered to removepyridine hydrochloride. The filtrate was washed with a dilute aqueoussolution of sodium bicarbonate, and then was washed with water untilneutral toward litmus paper. It was then stripped by distillation to akettle temperature of 100 C. under a pressure of less than 2 mm. ofmercury. The desired 5,5'-diethyl- 2,2 dioxo 4,4 dipropyl pyro 1,3,2dioxaphosphorinane was secured in'90% yield, based upon thephosphorus-containing reactant, in the form of a clear, colorless liquidhaving the following properties: 11 =1.4659; percent'purity=99 (bysaponification). It was free from chlorine, and had a salt content equalto 0.01 cc. of norm n HClO /gram.

caut on P-0 maintained at 100 C. there were added slowly 447 grams (2.25mols) of 2-chloro 5-ethyl-5-methyl-2-oxo-1, 3,25-dioxaphosphorinane.After an additional 3% hours i at this temperature, the reaction mixturewas cooled and Following the procedure described in Example 5, 1 mol" of2-chloro-4,6-dimethyl-2-oxo-1,3,2-dioxaphosphorinane was reacted with1.1 mols of anhydrous sodium acetate suspended in toluene. The reactionwas filtered and the desired product was extracted from the residueusing dry acetone. Upon removal of the acetone under vacuum, 84 grams of2,2'-'dioxo-4,4',6,6'-tetramethyl-pyro-1,3,2- dioxaphosphorinane wassecured in the form of white crystals having the following properties:melting point=160-166 C.; percent 'P=19.40 (theory=19.72); percentC=37.65 (theory=38.22); percent I-l;= 6.26

phosphorous-containing reactant, was secured.

EXAMPLE" 7 filtered. The, filtratewas stripped by distillation to akettle temperature of 90 C. underlS mm. of mercury pressure. Theresidual solid'was washed with 500 cc.

u: of ethyl ether, filtered and dried to'recover .193 grams of5,5-diethyl-5,5'-dimethyl-2,2 dioxo pyro-1,3,2-dioxaphosphorinane, whichhad the following analysis: percent- P=l8.30 (theory=18.10); percentC=42.38 (theory=42.11); percent H='6.98)- theory =7.06); M.P.=155-159 C.t 3

EXAMPLE 10 To an agitated suspensionof 316jgrams of anhydroussodiumacetate (3.8 mols) in 1400 grams of toluene maintained at 100 C.there were added slowly over 4 5 minutes 744 grams.t (3.5 mols) of2-chloro-5-methyl-2- sodium bicarbonate wasadded and the mixturethereafter washed with SOO cc cf-distiIIed water. The mixture wasstripped by distillation to a kettle temperature of in 300 grams-oftoluene held at 100 C., the'rewere added dropwise 113 grams (0.5 mol) of2-chloro-5-ethyl- ,2-oxo-4-propyl-1,3,2-dioxaphosphorinane. 'Afterg30minutes more at this temperature, the reaction mixture was washedwith 800 cc. of water, and the. oil layerwhich then separated wasstripped by distillation to a kettle a temperature of- C. underapressure of less 2 mm of mercury. The almost colorless residue tillationto a kettle temperatureof 155 C. under a preso kll. grams contained28.6% of butyric 'anhydride. A u gram sample of this residue'was furtherstripped by dis-1 y sapoui-" C. under 2 mm.-of mercury pressure. 421grams of 5,5-dimethyl-2,2 -dioxo-5,5'-dipropylpyro-1,3,2-dioxaphosphorinane were obtained. EXAMlLE 11 123 grams of asemiprepolymer preparedtherefrom by reaction with wtolyle'n'ediisocyanate (28.8% total free 0.11 gram. potassium laurate and 40-44gramstrichlorm monofluoromethane; The foamed productj'was curedforgrams'of a mixture comprising 86 percent by weight of a propyleneoxideaddition product of 1,1,3-

t1is(hydroxyphenyl) propane (Hydroxyl No.- 261). and 14' percentby-weightof -1",2,6-hexanetriol were mixed with EXAMPLE 12 of Test forFlammability of Plastic Foams and Sheeting, ASTM D-1692-59-T. In thistest the flame of a Bunsen burner, having a blue cone of about 1 /2inches in height, is applied separately to the front edge of ten foamspecimens, 6" x 2" x /2", and allowed to remain in contact therewith fora period of sixty seconds. The extent of burning is considered thefurthermost point reached by the flame front whereas the burning rate ininches per minute is a measure of the time necessary for the flame frontto consume five inches of the foam speci- 100 grams of a propylene oxideaddition product of sorbitol (Hydroxyl No. 500) and 134 grams of asemiprepolymer prepared therefrom by reaction with tolylene diisocyanate(29.9% total free NCO) were mixed with 1.0 gram dibutyltin dilaureate,0.6 gram of a silicone oil surfactant (siloxane-oxyalkylene copolymer),0.1 gram potassium laurate and 49 grams trichlorornonofluoromethane. Thefoamed product was cured for 10 minutes at 70 C. 10

. men. A sample is udged non-burning if no evidence of EXAMPLE 13ignition, such as flame or progressive glow, is seen in each 100 gramsof material comprising 80 percent by weight Specimen after removal ofthe flame. If the flame front f a propylene id ddi i product f 1 1 3- i(h of two or more specimens reaches the five inch markdroxypheny1)propane blended with a propylene oxide the sample is judgedburning? A samPle is judged addition product of glycerol to a. HydroxylNo. of 372 self-extinguishing When ignition 0f the ten specimsns weremixed i h percent by i h of a propylene gives an extent of burning lessthan five inches. The term oxide addition product of diethylenetriamine(Hydroxyl flame-resistant as p y herein is used to Character- No. 682).To thi mixture wa added 118,5 grams f ize a material which does not burnreadily. The terms a semiprepolymer prepared from a mixture comprising20 b g, se f-cXt nguishing and non-burning are a propylene oxideaddition product of 1,1,3-tris(hydroxydefi ed n accordance W th theabove test.

phenyl)propane blended with a propylene oxide addi- The data tabulatedin Table I below illustrates that tion product of glycerol (29.4% totalfree NCO), 0.5 polyurethane foams prepared according to the inventiongram of a silicone oil surfactant (siloxane-oxyalkylene can be readilyrendered flame-resistant through use of copolymer), 0.2 gram dibutyltindilaurate, 0.1 gram pocyclic pyrophosphates.

Table I Urethane, Example 11 11 11 11 11 11 11 12 13 13 14 15 15 15 15Pyrophosphate,

Example 4 4 10 10 9 1 1 9 4 9 9 4 4 2 Weight percent P... 2. 0 1. 5 2.0 1. 5 2. 0 2. 0 1. 49 2. 5 1. 5 2. 5 2. 5 1. 5 1. 5 2. 5 Weight;percent Sb20a 0 2.0 0 2.0 0 0 4 0 2.0 0 0 0 2 0 Density, lbs. 1. 9 2. 02. 0 1. 9 1. 9 2.1 2. O 1. 9 2. 0 2.1 2. 2 2. 1 2. 1 2. 7 1. 8Appearance AAA AAA BBB AAA BBB AAA AAA AAA AAA AAA AAA AAA AAA AAA AAAASTM Class S S S S S S S S B S S S S S B Rate or Extent-.. 2.2 2.0 2.6 1. 6 1.9 3. 5 3.1 2.1 3.3 1.8 2.6 1.5 1 9 3.2 3. 3

in. in. in. in. in. in. in. in. 1pm. m. m. in. in. in. 1pm Ig/B 13/5614/ 7 13/62 13/32 13/42 10/79 12/57 12/4 /121 1 3 11/63 11/35 8/41 20/621 Ignition time in seconds/extingnishrnent timein seconds. 2 Theappearance of the foam lsrated by a three-letter code with the firstletter estimating cell size, the second letter uniformity of cell sizeand the third letter bulk flaws (splits, ridges, burns, etc.) wherein:

1st Letter I 2nd Letter 3rd Letter A=Flne. Good. None. B=Medium. Fair.Minor. 0 =Large. Poor. Severe.

tassium laurate and 41 grams trichloromonofiuorometh- What is claimedis: I ane. The foamedproduct Was cured for 10 minutes at l. A method forthe preparation of flame-resistant 70 polyurethane foams in which amixture consisting essen- EXAMPLE 14 g tlally of a polyether having atleast two active hydrogens,

a catalyst, an organic polyisocyanate, a blowing agent and a minoramount of a phosphorus compound corresponding to the formula:

100 grams of a propylene oxide addition product of ot-methylglucosideand 124.5 grams of a semiprepolymer prepared therefrom (28.6% total freeNCO) were mixed with 0.6 gram of a silicone oil surfactant(siloxane-oxyal- R2 kylene copolymcr), 0.6 gram dibutyltin dilaureate,0.2 R L 0 gram N,N,N',N'-tetramethyl-1,3-butanediamine, 0.1 grampotassium laurate land 41 grams trichloromono- 9 fluoromethane. Thefoamed product was cured for 10 Rr minutes at 70 C. a 1

. EXAMPLE wherein R, R R R and R respectively, designates a grijlms Of aP py OXlde addition p l s' of radical of the class consisting ofhydrogen and the lower 4,4'-diammodiphenylmethane (Hy r y and alkylgroups; and n is a number of the class consisting 104.5 grams of ascmiprepolymer prepared thereiromby of 0 and 1, is reacted to producesaid foams.

reaction With tolylene diisocyanate (303% total fre i :2. The method ofclaim 1 wherein thephosphprus NCO) were mixed With 0.7 gram dlb tyltindilaurate, compound is a pyro-Z-oXo-l,3,2-dioxaphosphorinane. 0.7 gramof a slhcone 011 surfactant (siloxane-oxyalkyl- 3. The method of claim 1wherein the phosphorus ene copolymer),'0.l1 gram potassium laurate and",44 compound isa pyro-Z-oxo-1,3,2-di0xaphospholane.

grams of trichloromonofinoromethane. The foamed 4. The produce producedby the method of'c'laim 1.

product .was cured for 10 minutes at 709 C. 5. A method for thepreparation of flame-resistant Polyurethanefoams, as prepared n Examples11;t o polyurethane foams in which a mixture consisting essenl 5, wereblended prior to foaming with varying amounts 7 tially of apolyqxyalkylene l l, a catalyst" an organic of cyclic pyrophosphates andtested for flammability "polyisocyanate, afluorocarbon blowing agent anda'minor characteristicsin accordance with the ,Tentative Method Z amountof a phosphorus compound sutficient to provide 13 a phophorus contentbetween about 0.25% and 5.0% by weight corresponding to the formula:

wherein R, R R R and R respectively, designates a radical of the classconsisting of hydrogen and the lower alkyl groups; and n is a number ofthe class consisting of 0 and 1, is reacted to produce said foams.

6. The method of claim 5 wherein the phosphorus compound is apyro-Z-oxo-1,3,2-dioxaphosphorinane.

7. The method of claim 5 wherein the phosphorus compound is apyro-Z-oxo-1,3,2-dioxaphospholane.

8. The method of claim 6 wherein the phosphorus compound is5,5-diethyl-'2,2-dioxo-4,4'-dipropyl-pyro-1, 3,2-dioxaphosphorinane.

9. The method of claim 6 wherein the phosphorus compound is5,5-dibutyl-5,5-diethy1-2,2'-dioxo-pyro-1,3, 2-dioxaphosphorinane.

10. The method of claim 6 wherein the phosphorus 14 compound is2,2'-dioxo-5,5,5',5'-tetraethyl-pyro 1,3,2-dioxaphosphorinane.

11. The method of claim 6 wherein the phosphorus compound is4,4'-dimethyl 2,2 dioxo-pyro-1,3,2-dioxaphosphorinane.

12. The method of claim 6 wherein the phosphorus compound is2,2'-dioXo-4,4',6,6'-tetramethyl-pyro 1,3,2- dioxaphosphorinane.

13. The method of claim 6 wherein the phosphorus compound is5,5'-diethy1-5,5'-dimethy1-2,2'-dioxo-pyro-l, 3,2-dioxaphosphorinane.

14. The method of claim 6 wherein the phosphorus compound is5,5'-dimethy1-2,2-dioxo-5,5'-dipropyl-pyro- 1,3,2-dioxaphosphorinane.

15. The method of claim 7 wherein the phosphorus compound is4,4'-dimethyl-2,2'-dioxo-pyro 1,3,2 dioxaphospholane.

16. The product produced by the method of claim 8. The product producedby the method of claim 9. The product produced by the method of claim10. The product produced by the method of claim 11. The product producedby the method of claim 12. The product produced by the method of claim13. The product produced by the method of claim 14. The product producedby the method of claim 15.

No references cited.

1. A METHOD FOR THE PREPARATION OF FLAME-RESISTANT POLYURETHANE FOAMS INWHICH A MIXTURE CONSISTING ESSENTIALLY OF A POLYETHER HAVING AT LEASTTWO ACTIVE HYDROGENS, A CATALYST, AN ORGANIC POLYISOCYANATE, A BLOWINGAGENT AND A MINOR AMOUNT OF A PHOSPHORUS COMPOUND CORRESPONDING TO THEFORMULA: